Television system



f4/fen v/mf NVENTOR BY M r fseerence A. E. DU MONT TELEVISION SYSTEM Filed April 2l, 1931 1. l Vn "L 3.4. nf.. C..

FIPa'lQe` V Dec. 18, 1934.

ATTORN EYS Patented Dec. 18, 1934 y IUNITED STATES PATENT ori-leaf vTELEVISION SYSTEM Application Api-i1 21, 1931, seria1Np.5s1,css '.1

invention relates to electro-optical systems, and -with particularity to a direct vision television system. Q'

E"-"A'rrobect of the invention is to provide a methof television without using electrical transmiseun channels. f

Another objectA of the invention is to provide l'what may a direct television producing A feature of the invention relates to the employment of a high powered light source which is capable of being viewed over very long distances, said light source being modulated in accordance with television signals.

- Other features and advantages not speciiically enumerated will be apparent after a consideration of the following detail descriptions and the appended claims. Heretofore in television systems it has been the customary practice Yto translate the shade values of the subject or object into corresponding modulated currents and these currents have been transmitted over wire or radio channels to distant points at which the image is to be reproduced. The Apresent invention contemplates 'a television system wherein the television 'images ,may be reproduced from the television signals at distant lpoints without employing wire -or radio channels. `lln accordance with the present invention it is proposed to employ a high-powered light source such as a water cooled neo or a lamp such as an aerial bgipgn lama, It is a well known fact that these high-powered lamps are capable of being seen over great distances. In some cases the lamps are visible over a distance of fteen to twenty-rive miles. Advantage is taken of this fact, in accordance-with the present invention, to enable images to be integrated from the light impulses, whereby the images may be broadcast and reproduced by direct vision, at such distances as would be impossible without utilizing the presen t invention.

Accordingly in the drawing the numeral 1 represents a suitable location for the television broadcast station such as a tall building or other convenient location for what may be termed a television beacon, capable of being viewed throughout a wide range. In the drawing this beacon is represented schematically in the form of a coiled tube 2, which is preferably water cooled so as to enable the said tube -to be operated at high current densities. For c ,tube

/jll'mlfih may have a of neonpnpth w siagne of varying its intensigm on a suitable support or tower 3 on top of the building 1, and the yelectrodes of said lamp are connected by wires 4 and 5 to any well known form of televisigg transmitter within the Abuilding. The transmi er .1s represen ed schematically in the drawing by the rotatable scanning disc 6, such as shown in Patent 1,679,086granted to C. F. Jenkins on July `31, 1928, and a light sensitive cell 7, the output of Ywhich is connected to a suitable amplifying device .8. In accordance with well known television principles, as the device 6 rotates, the subject or object whose image is to be reproduced at a distance, has its elemental areas tested for shade and translated into 'core responding photo-electric :currents vfromjthe device 7. These currents after suitable amplication are impressed upon .the lamp 2, which there- Afore 'varies in brilliancy in accordance' with `the shade characteristics v4of the image to be transmitted..r. ..1 l ,c .l at.-

' I wiupe derstpd a bias' source for maintailmil v ummatedemihmighmisignals in Ie;

alle @angemessenes Leaieetthelahm 'regains at es lit, but has its ',b ancy; yariaegw *Since the llr'is'preferably of an extremely high powered type, itis capable of being seenat .very great distances, and in orderto 'reproduce the images it is necessary to employ a telescope in vconjunction with a television scanning device. For example, "the drawing shows apparatusfor reproducing 'the images at four widely separated points which may be miles distant from the broadcasting television lamp 2. For the purpose of reproducing the image the telescope or light collecting device 9 at each distant locality is trained upon the distant television beacon 2 until the scanning eld of the associated scanning device 11 Vappears to be uniformly illuminated. The observer then views the disc through an adjustable optical system 10 until the image appearsinproper form. It will be understood, of course, that the scanning device 11 used in conjunction with the optical members 9 and 10 is substantially, or at least optically, the same as the scanning device 6 at the broadcast station. That is to say, the member 11 must have the same number of scanning elements as the member 6, and must rotate in synchronism therewith. Any well known method of synchronism may be employed.

By this system, therefore, the usual wire or radio channels are eliminated, thus eliminating the usual modulating and carrier apparatus at the transmitting station, and completely eliminating at the radio receiving station, radio pick-up and amplifying equipment ordinarily employed in present television systems using wire or radio transmission.

As an example of one particular use to which the invention may be put, may be mentioned airplane direction. The lamp 2 may be situated at an airport and its intensity may be varied so as to produce a letter, or design, characteristic of the location of the airport. For example, the television scanner 6 may produce, in conjunction with the cell 7, currents corresponding to the letter A, which, for example, may designate the airport. In other words, the lamp 2 Will have its brilliancy varied the same as if the letter A were being transmitted by ordinary television methods. The airplane would be equipped with a telescope or optical system similar to the members 9 and l0 of the drawing. and also with a rotatable scanner 11. This scanner "il may be provided with a local speedfrntrol device which is designed to rotate Le said scanner 11 at the same speed as the scanner 6. The pilot, therefore, will train his telescope with the scanner 11 therein upon the lamp 2, and will notice the reproduction of the characteristic design or letter of the airport, and will immediately be apprised of bis location.

It will be understood, of course, that in this use it is not necessary to employ television scanning apparatus to modulate the light source 2, for example, a single record may be made which produces currents that would be the same as if the television scanner had been employed, these currents being representative of the characteristic mark or designation of the airport. In this system of course, preferably all the airports will be designed to transmit distinct letters or signs and will be operated at a single frequency, and there will be no interference since reliance is not placed upon radio transmission between the broadcasting station and the airport.

It will be further understood, of course, that the invention is not to be limited to the particular use above described, but is capable of use in any System where intelligence is to be transmitted over a great distance without the use of 4radio or Wire transmission channels.

By the expressions television scanning device" is meant herein a device which is capable of analyzing an area to be reproduced, in successive elemental portions, or a device which is capable Di' integrating an area to be reproduced in elemental portions such, for example, as disclosed in Jenkins Patent No. 1,679,086. By the term television reproducer is meant herein a device or combination of devices for reproducing an image or an object or other visual representations at a distance.

What is claimed is:

1. 'Ihe method of producing and receiving television images 'which comprises broadcasting a mcdulated'high powered light capable of being seen throughout a Wide area, optically producing images directly of said light at Widely separated rpointsjand telescopically viewing said light images at lsaid Widely separated points through individual television scanning devices.

2. 'I'he'method according to claim l in which the light is stationary and has its intensity modulated in accordance with shade characteristics of a visual representation to be broadcast.

3. AIn a system for broadcasting intelligence, the combination of a high-powered light, means for optically producing a direct image of said light at a distant point, means for modulating said light in accordance with the intelligence to be transmitted, and means for telescopically viewing said light directly at a distance including a television scanning device.

4. In a system for transmitting intelligence to a distance, employing light waves for transmission, the combination of a broadcasting television light beacon and a plurality of distantly located television scanning devices, means for modulating said beacon, and telescope means associated with each scanning dence for collecting light from said beacon and projecting it upon the associated scanning device in the form of a uniform light field.

5. In a message transmission system the combination of a television beacon, means for modulating said beacon, a plurality of individual television scanning devices located at a distance from said beacon, and telescope means associated with each scanning device for training the light from said beacon upon the associated scanning device in the form of a uniform light iield.

6. In a system for broadcasting messages, the combination of a high powered gaseous conduction lamp, means for modulating the light of said lamp with message signals, means for supporting said lamp at a high elevation above the earth, a plurality of individual'television scanning devices adapted to be trained upon said lamp to reproduce the messages at distant points by direct television, and means associated with each scanner for projecting thereupon a direct image of the light from said lamp.

ALLEN B. DU MONT. 

